CNN’s logo is hand drawn and, while there are many lookalike (but knockoff) fonts available out there, it’s not technically a typeface, but rather a hand drawn glyph.
For most of its other font needs, however, CNN uses a custom font called CNN Sans. The font is used in most of its on air graphics, including most prominently in the banners that run along the bottom of the screen. There are also versions of it used on the network’s website and mobile apps.
This post was last updated September 21, 2018 and, although it was believed to be accurate at that time, this information may have changed since this time. Although reasonable efforts are made to ensure the accuracy of this answer, it cannot be guaranteed and you are encouraged to verify any details independently.